[TOMT] Trying to find an impossible very old movie

Hi everyone ! I’ve been trying to find an old ( gore or horror movie ? ) I watched maybe 20 years ago, I was a kid.

The story is about a couple that goes on vacation on a cruise. There’s this scene at night when everyone is eating on a long rectangle table with a white cover, they are wearing fancy clothes. Someone ( I can’t remember who and why ) poisons the husband's food which turns him into a monster and the whole movie happens during the night when he hunt/kill/eat? the passengers. There’s a scene when some of them are hiding in the boat’s hold ? ( from memory, it looked like an underground with pipes on the ceiling ) Water reaches their knees and the monster underwater grabs some of them and kill them, blood everywhere in water. At the end of the movie, they’re rescued by something similar to S.W.A.T and the monster is killed by being exploded using bombs in a large bin or a large box, I’m not sure but he was trapped in something ( before dying I have a memory of the monster remembering his girlfriend and I think he was planing to propose to her on the cruise ? ) The girlfriend survived. Note that during the movie, it’s hard to see what the monster looks like ( on purpose I believe )

Once in a while I remember this movie I watched on vacation in Dakar on TV and I’ve never been able to find it.

( also English isn’t my first language, I’m French. )